PROJECT SUMMARY/ABSTRACT ? IMAGING CORE The host response to pathogen infections is not confined to a single tissue, thus maintenance of homeostatic immune surveillance and the development of protective immune responses require that cells in the immune system constantly patrol the entire body, efficiently crossing multiple tissue barriers. Furthermore, in their target sites, immune cells often have to find customized tissue-specific solutions to effectively identify and eradicate pathogens. As such, the direct observation of leukocyte adhesion, migration and communication in lymphoid and non-lymphoid tissues with microscopy is one of the most important experimental approaches. The Imaging Core (Core B) has been established based on a stated need of PPG investigators and is designed to draw on the considerable experience of its key personnel to provide expertise and specialized equipment in the design and execution of in vivo imaging studies of effector T cell functions in infected tissues. The main missions of the Imaging Core are as follows: 1. To provide state-of-the-art imaging capabilities in conducting specific experiments regarding leukocyte adhesion and migration as well as cell-cell interactions during local immune responses in as many as six dimensions (i.e. 3D-space, time, color, fluorescence signals). 2. To develop a novel hyperspectral multiphoton microscopy for multicellular in vivo imaging. 3. To provide technical assistant for analysis of the collected image data. 4. To provide assistance in the planning of in vivo animal studies by offering standardized infectious/inflammation models and a custom-designed environment with appropriate biosafety conditions for the generation, housing and intravital microscopy analysis of live cell cultures, explanted tissues, and infected mice. The Cores have already been highly effective in achieving some of these goals by providing service that both facilitates research and fosters collaborations between investigators, and by enabling development of novel in vivo animal models and imaging techniques.